1. Field of the Invention
The present invention relates to a reel around which a recording tape such as a magnetic tape used as a recording/playback medium for mainly computers and the like.
2. Description of the Related Art
Conventionally, a recording tape such as a magnetic tape is wound around a reel made from synthetic resin, and the tape is used as a data recording/playback medium (data backup) for devices such as computers. This is known as a recording tape cartridge where the reel is housed singly inside a case. The reel of this recording tape cartridge is formed from, e.g., a lower flange and hub integrally formed, and an annularly-shaped upper flange adhered to the upper peripheral edge of the hub. (See, for example, Japanese Patent Application Laid-Open (JP-A) No. 2001-135063.)
In a reel of this type of configuration, in a metal mold used to integrally form the lower flange and hub, a gate for injecting resin material is positioned so as to correspond to a position of the bottom wall portion of the hub. Accordingly, the resin material injected through the gate flows once into the “hub side” of the metal mold, and after that, flows to the “lower flange side” of the metal mold. This is because the hub is thicker than the lower flange. However, in a case of this type of flow of resin material, there is a problem in that shrinkage and the like occur because the cooling times of the hub and lower flange differ, and the lower flange deforms. This causes surface runout in the lower flange to increase. Further, if the hub deforms due to tight winding of the recording tape, there is a danger of the upper flange adhered to the hub also deforming.
Other reels are known, such as one where a hub having a bottom wall and an upper flange are integrally formed. The reel is formed by adhering an annularly-shaped lower flange to the peripheral edge of the bottom wall of the hub. (See, for example, Japanese Patent Application Laid-Open (JP-A) No. 2005-251272.) In this case, increase in surface runout in the upper flange can be suppressed, however, there is a problem in that, after adhering the lower flange to the hub, a reel plate made out of metal is fixed to the bottom wall of the hub. Accordingly, number of processes and manufacturing costs increase.
Here, in light of the above-described circumstances, the present invention provides a reel with which deformation of the flange and surface runout of the flange can be suppressed, without increasing number of processes and manufacturing costs.